Computer Systems

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CHAPTER 2

• Computer Systems

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COMPUTER GENERATIONS

• 1. VACUUM TUBES 1946-1959

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COMPUTER GENERATIONS

• 1. VACUUM TUBES 1946-1959
• 2. TRANSISTORS 1957-1963

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COMPUTER GENERATIONS

• 1. VACUUM TUBES 1946-1959
• 2. TRANSISTORS 1957-1963
• 3. INTEGRATED CIRCUITS 1964-1979

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COMPUTER GENERATIONS

• 1. VACUUM TUBES 1946-1959
• 2. TRANSISTORS 1957-1963
• 3. INTEGRATED CIRCUITS 1964-1979
• 4. VERY LARGE-SCALE INTEGRATED (VLSI) CIRCUITS
  1980- PRESENT

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SUPERCOMPUTERTERAFLOP TRILLION
CALCULATIONS/SECOND

• HIGHLY SOPHISTICATED
• COMPLEX COMPUTATIONS
• FASTEST CPUs
• LARGE SIMULATIONS
• STATE-OF-THE-ART COMPONENTS
• EXPENSIVE

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MAINFRAME
MIPS Millions of Instructions per second

• LARGEST ENTERPRISE COMPUTER
• 5O MEGABYTES TO OVER ONE GIGABYTE RAM
• COMMERCIAL, SCIENTIFIC, MILITARY APPLICATIONS
• MASSIVE DATA
• COMPLICATED COMPUTATIONS

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MINICOMPUTER

• MIDDLE-RANGE
• 10 MEGABYTES TO OVER ONE GIGABYTE RAM
• UNIVERSITIES, FACTORIES, LABS
• USED AS FRONT-END PROCESSOR FOR MAINFRAME

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MICROCOMPUTER

• DESKTOP OR PORTABLE
• 64 KILOBYTES TO OVER 128 MEGABYTES RAM
• PERSONAL OR BUSINESS COMPUTERS
• AFFORDABLE
• MANY AVAILABLE COMPONENTS
• CAN BE NETWORKED

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LAPTOPS SMALLER

• LAPTOP (OR NOTEBOOK) Briefcase type package,
  very portable, can be inexpensive, can connect to
  other computers or networks
• HAND-HELD (OR PALMTOP) Sub-miniature, wireless
  computer. Growing in sophistication and
  connectivity

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BASIC COMPONENTS OF COMPUTER SYSTEMS

• UNDERLYING STRUCTURE
• INPUT/OUTPUT
• BITS CODING SCHEMES
• ARITHMETIC LOGIC UNIT

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CENTRAL PROCESSING UNIT (CPU)
CONTROL UNIT
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BUSES
DATA BUS ADDRESS BUS CONTROL BUS
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TYPES OF MEMORY

• RAM Random Access Memory
• Dynamic Changes thru processing
• Static Remains constant (power on)
• ROM Read Only Memory (preprogrammed)
• PROM Program can be changed once
• EPROM Erasable thru ultraviolet light
• EEPROM Electrically erasable

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INPUT/OUTPUT

• TERMINAL
• POINT-OF-SALES TERMINALS
• AUTOMATIC TELLER MACHINES
• PUNCHED CARDS
• MAGNETIC INK CHARACTER RECOGNITION (MICR) Used
  by banks to process checks

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INPUT/OUTPUT

• OPTICAL CHARACTER RECOGNITION Scanned material
  translated into computer characters
• IMAGING Forms, documents, photos digitized for
  computer use
• BAR CODE LABEL Product label information read
  into computer. Can be used to track inventory

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INPUT/OUTPUT

• COMPUTER OUTPUT MICROFILM (COM) Computer rapidly
  generates microfilm documents for archive copies
  in small space
• VOICE RESPONSE UNITS Computer recognizes,
  generates verbal messages
• MULTIMEDIA Combines text, graphics, sound still
  images, animations, video

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HOW CHARACTERS ARE STORED IN COMPUTER MEMORY

• BIT Binary Digit. On/Off, 0/1, Magnetic/Not
• BYTE Group of bits for one character
• EBCDIC- Extended Binary Coded Decimal Interchange
  Code (8 bits per byte)
• ASCII- American Standard Code for Information
  Exchange (7 or 8 bits per byte)
• PARITY BIT extra bit added to each byte to help
  detect errors

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EXAMPLES OF BYTES
EBCDIC ASCII (assume
even-parity system)

• C 1100 0011 0 100 0011 1
• A 1100 0001 1 100 0001 0
• T 1110 0011 1 101 0100 1
• Note how sum for each byte is an EVEN
  number

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ALU CONTROL UNIT

• ARITHMETIC- LOGIC UNIT CPU component performs
  logic and arithmetic operations
• CONTROL UNIT CPU component controls, coordinates
  other parts of computer system

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COMPUTER FILES

• RECORD Data about a transaction arranged in a
  set of FIELDS, each holding a datum
• FILE A group of similar records, such as
  accounts receivable or payroll
• DATABASE The files of an organization, an
  electronic library

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COMPUTER FILES

• SEQUENTIAL ACCESS A sequence of files arranged
  in order, say alphabetically. Usually stored on
  magnetic tape or cartridge
• DIRECT ACCESS Records stored on a DIRECT ACCESS
  STORAGE DEVICE (DASD). Can move directly to any
  record

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DIRECT ACCESS STORAGE DEVICE

• HARD DISK Steel platter array for large computer
  systems
• RAID Redundant array of Inexpensive Disks
• FLOPPY DISK Removable disk for PC

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DISK PACK STORAGE

• LARGE SYSTEMS
• RELIABLE STORAGE
• LARGE AMOUNTS OF DATA
• QUICK ACCESS RETRIEVABLE
• TYPICAL 11 2-SIDED DISKS
• CYLINDER SAME TRACK ALL SURFACES

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THE STORED PROGRAM CONCEPT

• COMPUTER IS A BINARY SYSTEM
• PROGRAM A set of instructions telling the
  computer what to do
• INSTRUCTION Individual step or operation in a
  program
• MACHINE LANGUAGE Translated instruction
  understood by particular model of computer

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CONTROLLER

• LINK FOR INPUT/OUTPUT OR FILE DEVICES To CPU and
  memory of large computer systems
• HIGHLY SPECIALIZED PROCESSOR Manages the
  operation of attached devices to free the CPU
  from these tasks

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DATA CHANNEL

• SPECIALIZED INPUT/OUTPUT PROCESSOR (A COMPUTER)
  Takes over function of device communication from
  the CPU
• CORRECTS FOR SPEED MISMATCH BETWEEN SLOW
  PERIPHERAL DEVICES AND VERY FAST CPU

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SYMMETRIC MULTIPROCESSOR

• PROCESSORS (CPUs) ARE IDENTICAL, WITH EACH
  PROCESSOR OPERATING INDEPENDENTLY OF THE OTHERS
• USED IN MOST MAINFRAMES AND SOME MIDRANGE
  MACHINES

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PARALLEL PROCESSOR (PP)

• MULTIPLE CPUs INSTALLED AS PART OF A SINGLE
  COMPUTER SYSTEM Gives separate piece of program
  to each of the processors so that work on the
  program can proceed in parallel on the separate
  pieces

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MASSIVELY PARALLEL PROCESSOR (MPP)

• PARALLEL PROCESSING COMPUTER WITH MANY PARALLEL
  PROCESSORS
• 32 OR MORE Different CPUs capable of performing
  different instructions at the same time
• 1000 OR MORE CPUs must all carry out the same
  instruction at the same time

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CHAPTER 2

• Computer Systems